Microsurgery involves the manipulation of delicate membranes and vessels with a required accuracy often on the order of tens of microns, a scale at or near the limit of human positional ability [C. N. Riviere, R. S. Rader, and P. K. Khosla, “Characterisitcs of hand motion of eye surgeons,” presented at IEEE Engineering in Medicine and Biology Society, Chicago, 1997; M. U. Humayun, R. S. Rader, D. J. Pieramici, et al., “Quantitative measurement of the effects of caffeine and propranolol on surgeon hand tremor.,” Arch Ophthalmol, vol. 115, pp. 371-374, 1997.] Forces imposed by the tissue on the surgical tool during these manipulations are exceedingly small. Research indicates that tactile sensation tools interacting with an environment is an important factor in task performance. For example, vitreoretinal surgeons cannot “feel” the majority of interactions between the surgical instruments they are holding and the retinal tissue being manipulated [Gupta, P. and Jensen, P. S. “Surgical Forces and Tactile Perception During Retinal Microsurgery”, Second International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI), Cambridge England, Sep. 20-22, 1999.]. In other words, the forces being imparted on the retina by the medical practitioner through the use of a surgical tool are typically too small to be perceived by the medical practitioner's fingertips. As a result, the medical practitioner must rely primarily on visual feedback to position the instruments and to manipulate the retinal tissue.
Although the view through the operating microscope is quite good, prior studies have demonstrated that a lack of tactile and haptic sensation while performing manual manipulation tasks leads to both increased errors and increased task completion times. For example, it was demonstrated by Howe [Howe, R. D., et. al. “Tactile display of vibratory information in teleoperation and virtual environments.” Presence, 1995 4(4):387-402.] that manually inserting a peg into a hole using only visual information, although possible, took up to ten times longer to complete and had significantly greater positioning error than when tactile sensation was provided. Studies have also shown that a combination of at least two agreeing perceptual inputs significantly improves task performance [Sage, G. H. “Introduction to Motor Behavior: A neurophysical Approach”. Addison-Wesley Publishing: Reading, Mass., 1984.]. In addition, the visual feedback pathway is slow compared to both auditory and mechanical responses, thus making secondary perceptual input useful during manual manipulations [Patkin, M. “Ergonomics applied to the practice of microsurgery”, Aust NZ J Surg, 1977, 47(3):320-329.]. We therefore know that A) many interactions between the surgical tool and the tissues in particular applications are too small to be felt by the medical practitioner, B) performing manual tasks without a sense of touch increases positional errors and task completion times, and C) incorporating multi-sensory information (i.e. sight+touch or sight+auditory) significantly increases manual task performance. Since relying on visual feedback alone has been shown to both increase the length of manual manipulation tasks and reduce task accuracy, augmenting tactile perception during microsurgery can potentially reduce surgical execution time while increasing surgical precision.
It would thus be desirable to have improved surgical devices that provide a medical practitioner with enhanced perceptual feedback during the manipulation of tissue in the form of tactile sensations and/or auditory feedback, thereby improving the performance, accuracy and speed of the surgical procedure.